As disclosed, for example, in U.S. Pat. No. 4,805,217 corresponding to JP-A-H5-31856, an on-vehicle radio receiving apparatus has been proposed that receives a radio broadcast signal and automatically records sound information contained in the broadcast signal on a memory. The recorded sound information can be played back at any time. Since a driver is focused on driving a vehicle, the driver may miss to catch important information contained in the radio broadcast signal. Such a radio receiving apparatus allows the driver to get the missed information later by playing back the recorded sound information.
Generally, when a radio station is changed, a reception frequency of a radio receiving apparatus is manually changed, for example, by tuning a tuning knob or pressing a preset button. As disclose, for example, in JP-A-H5-183392, an on-vehicle radio receiving apparatus has been proposed that has an network follow function that automatically changes a reception frequency in accordance with a strength of a received radio broadcast signal. The network follow function is described in detail below.
A radio broadcast signal has a limited transmission range. In radio broadcasting, therefore, radio stations are respectively distributed in regions to achieve nationwide coverage, and adjacent radio stations broadcast at different frequencies. When the same radio program is broadcast in a wide area, multiple radio stations located different regions broadcast the same radio program at different frequencies.
In the case of long-distance driving, when the radio receiving apparatus presently receives a radio program from a first radio station, the radio receiving apparatus may be able to receive the same radio program from a second radio station different from the first radio station. In such a case, if a first strength of a first radio broadcast signal received from the first radio station is less than a second strength of a second radio broadcast signal received from the second radio station, the network follow function causes the radio receiving apparatus to automatically switch from the first radio station to the second radio station.
In the conventional radio receiving apparatus having the recording function, when a radio station (i.e., reception frequency) is manually changed, a certain period of time is required to complete the change of the radio station. As a result, the recorded sound information probably has silence and noise. One approach to prevent the recorded sound information from having silence or noise is that the recording function is stopped whenever the radio station is changed. However, this approach results in an intermittent recorded sound. When the radio station is automatically changed by the network follow function, the change of the radio station is instantly completed so that the recorded sound does not has silence and noise. Therefore, in the case where the radio station is automatically changed, there is no need to stop the recording function.